The invention relates to a drive unit for a wiper system of motor vehicles having a wiper shaft or pivot pin with a fastening section for connecting to a crank arm.
In wiper systems of motor vehicles several drive units are needed to transform the rotary motion of an electric motor into a pendular motion of a wiper. A problem generally experienced is how to fix a first element onto a crank arm or onto a crank, whereby the fastening area of the first element is anchored in a respective aperture of the crank arm. The first element could be, for instance, a wiper shaft or a pivot pin, especially a ball pivot pin.
A drive unit for wiper systems in which a crank arm is fixed in a middle fastening area of a wiper shaft is already known. The fastening section of the wiper shaft to which the wiper arm is connected is disposed on one side of this crank arm and is usually provided with a threaded section and a knurl. On the other side of the crank arm, a bearing section of the wiper shaft is rotatively located in a bearing bushing. In order to provide an unrotatable connection stable inform between the crank arm and the wiper shaft, the typical wiper shaft comprises an extending profiled section that is pressed into the respective aperture in the crank arm. In order to secure the crank arm in the axial direction of the wiper shaft, arresting shoulders serving as holding elements for the crank arm are punched out of this profiled section. Because of this profiled section in the middle of the wiper shaft it is relatively expensive to manufacture such a drive unit.
Drive units with a double ball pin anchored at a crank arm for being linked to further drive units which, for instance push rods, are also known. So far this pivot pin has been soldered to the crank arm in the fastening area.